1. Field of the Invention
The present invention relates generally to the field of water purifiers and more specifically to the field of water-cooled distilling apparatuses.
2. Statement of the Problem
In many areas of the world, tap water is not suitable for human consumption. This is true in numerous third world countries and even in developed countries like the United States when a water treatment facility fails due to equipment malfunctions or natural disasters. In such cases, harmful chemical and biological contaminants must be removed before the water can be safely consumed.
Methods and apparatuses are available to help remove these harmful contaminants from the water, including the use of carbon filters, ultra-violet (UV) light, ozone, and reverse osmosis (RO). However, these methods are often expensive and/or require extensive maintenance. Many of them also do not remove all of the contaminants or are inefficient. Alternatively, bottled water can be purchased; however, bottled water is expensive and not always available. In addition, the quality itself of some bottled water may be questionable.
Another option is to remove these contaminants from the water by distillation. There are three general categories of conventional distillers: (1) air-cooled distillers that cool and condense the steam using airflow, (2) high volume water-cooled distillers that cool and condense the steam by heating up large volumes (e.g., seven gallons) of coolant water to produce one gallon of distillate, and (3) hybrid water-cooled distillers that use moderate volumes (e.g., three to five gallons) of coolant water that is heated up and partially evaporated to produce one gallon of distillate. Distillation is acknowledged by most experts to reliably produce the best quality water (typically 99.9% pure). However, despite their effectiveness, distillers are not widely accepted by consumers because distillers typically have slow production rates, can be loud when fans are used to cool the steam (i.e., in air-cooled distillers), and produce excessive heat in the room in which they are used. They also can be difficult to clean (e.g., mineral scale) and usually require a carbon filter to obtain the best results.
Although high volume water-cooled distillers do not produce excessive room heat, such distillers normally cool the steam by flooding the outside of the condensing chamber with a continuous stream of cold water. These distillers usually also require a dedicated 220 volt circuit, a separate water feed line, and a coolant-water waste line. In addition, the distillers typically require at least seven gallons of cold water as indicated above to condense enough steam to produce one gallon of distillate. Even then, when only seven gallons of coolant water are used, the coolant water is usually so hot (about 200xc2x0 F.) that it can damage household sewer pipes. Therefore, most water-cooled distillers commonly run ten gallons of coolant water down the drain for every one gallon of distillate produced. Though effective, such distillers can often cost anywhere from $1000 on up.
Hybrid water-cooled distillers (e.g., for use on wood stoves or camping stoves) do not use as much coolant as the high volume distiller, but they can only operate effectively at low power inputs (e.g., 1000 watts or less once the coolant water becomes hot and must be subsequently evaporated). As such, these distillers have a very low output rate (e.g., three to four hours to produce one gallon of distillate) and are typically very large, often as large as a five gallon can. In addition, these distillers do not work well on conventional household electric ranges because of the effect of digital switching. That is, when a 2500 watt electric burner is turned to the xe2x80x9cmediumxe2x80x9d setting, the burner element does not draw 1250 watts, but instead it draws 2500 watt pulses (i.e., the burner element is switched on and off repeatedly by a thermostat) for an average of, for example, 1250 watts. However, the steam production in a distiller follows the wattage nearly instantaneously. Thus, during a pulse (.g., 2500 wafts), more steam is produced than can be handled by the distiller and must be vented and lost to the surrounding atmosphere. As a result, the efficiency declines and the volume of distillate cannot be accurately predicted (e.g., from one burner setting to the next).
3. Solution to the Problem
The water-cooled distilling apparatus of the present invention solves the problems discussed above. Specifically, the distilling apparatus of the present invention is of compact design (e.g., only 11.5 inches in diameter and height) and purifies the raw water so that it can be safely consumed. In doing so, a screen in the boiler prevents particles in the raw water from becoming entrained in the steam, thus eliminating the need for any post filtering (e.g., carbon filtration). In the preferred embodiment, no fans are required, reducing the noise and heat output into the room. Instead, heat from the steam is driven through a sufficiently large surface area into coolant water, which evaporates to the surrounding atmosphere preferably in a substantially one-to-one ratio (i.e., coolant evaporation to distillate production). This evaporation temporarily raises the humidity in the room but does not noticeably increase the temperature in the room. The distilling apparatus of the present invention also generates little, if any, waste water and eliminates the need for expensive and cumbersome drainage. It also produces distillate at a relatively high rate. Further, the distillation apparatus of the present invention can be used on any conventional household electric or gas range, with predictable production rates, and is easily disassembled (e.g., for cleaning and storage). In addition, the distilling apparatus of the present invention costs less than most conventionally available water purifiers. It also operates essentially at atmospheric pressure (e.g., typically no more than 0.01 psi above ambient pressure, which is comparable to pressures produced when cooking with conventional, covered lightweight pots and pans).
The present invention involves a water-cooled distilling apparatus for generating or forming purified water from raw or contaminated water. The raw water is placed in a boiler, preferably rated at about 2500 watts, and a self-regulating screen is placed within the boiler. The screen includes a sidewall portion that extends downwardly from a central portion and substantially about the perimeter of the central portion. Raw water is poured into the boiler and initially covers the screen (i.e., when the raw water is cooler than the boiling temperature of water). As the water beings to boil, the screen rises to the surface of the raw water and then floats above it on the steam bubles. The height of the central portion of the self-regulating screen above the raw water automatically adjusts proportionately to the rate of boil (i.e., it increases as the rate of boil increases and decreases as the rate of boil decreases). In this manner, the screen is self-regulating in that it proportionately exposes more or less surface area of the sidewall portion of the screen depending upon the rate of boil. The self-regulating screen is dimensioned to cover substantially all of the exposed raw water even at the highest rate of boil so that any particles of the raw water are prevented from passing by or around the screen and becoming entrained in and contaminating the steam rising from the screen. The central and sidewall portions of the screen provide surface area on which a water film initially forms from the raw boiling water. Secondary, clean steam is then generated from and rises from the water film on the screen.
A multi-level, cooling tray assembly in the preferred embodiment is placed over the boiler and screen and the steam rising from the screen is directed into the cooling tray assembly. Preferably, an inverted, substantially V-shaped deflector at each level in the cooling tray assembly directs the steam substantially along a predetermined path into and through a condensing area formed between a coolant water reservoir and a collection tray at each level. The steam collects on the bottom surface of each coolant water reservoir and in a preferred embodiment, the bottom surface of each coolant water reservoir is dimpled and sandblasted to facilitate steam condensation and distillate drip. Heat is transferred from the steam into each coolant water reservoir causing the coolant water to evaporate and the steam to condense. Turbulence rims on the outer perimeter of the cooling tray assembly direct the evaporation away from the cooling tray assembly so that the coolant water continues to efficiently remove heat from the steam to form distillate or purified water. The purified water drips onto and flows down each tray to a collection cup placed beneath the bottom tray immediately above the boiler and screen. The purified water exits the cup through a transfer pipe and flows to a collection vessel. Preferably, a fill alarm on the coolant vessel indicates that the purified water in it has reached a predetermined level (e.g., the vessel is full).
The distillate apparatus of the present invention preferably has two pressure and vacuum releases. In this regard, a steam release is formed at the top of the cooling tray assembly by a cover placed over a steam vent. The cover has a rim with ridges formed about its perimeter and after air in the distilling apparatus is initially driven out through it, the condensing steam fills the ridges between the cover and the steam vent and forms a water seal. The cover""s water seal opens to release steam when the pressure within the boiler and the cooling tray assembly exceeds a predetermined level. The water seal around the cover is also broken to let ambient air into the cooling tray assembly and the boiler whenever a vacuum is created therein, such as when cold water is added to the coolant water reservoirs. The covered vent serves as a primary pressure and vacuum release; however, the transfer pipe preferably also has a water trap that serves as a secondary pressure and vacuum release for the distilling apparatus.
In the preferred embodiment, purified water is produced substantially at a one-to-one ratio relative to evaporation from the water coolant reservoirs. Other features of the present invention include that the screen is self-cleaning, the bottom surface of the boiler is dark colored and substantially concave to reduce heat loss, and a wave dampening baffle is provided in each coolant water reservoir. The baffle has at least two members that are pivotable about one another so that the baffle substantially conforms to the sloped floor of the coolant water reservoir. The baffle can also be used as a fill-depth guide.
These and other advantages, features, and objects of the present invention will be more readily understood in view of the following detailed description and the drawings.